Wood preservative and method for producing same

ABSTRACT

A synergistic aqueous wood preservative composition comprising a copper compound and penflufen. The copper compounds of the compositions of the invention may be soluble, partially solubilized or micronized particles. The penflufen of the compositions of the invention may be solubilized, emulsified or particulate. The wood preservative compositions of the present invention are surprisingly provided as stable dispersions and confer surprising and unexpected resistance to treated wood and wood products.

This application is a divisional of U.S. patent application Ser. No.15/840,877, filed Dec. 13, 2017, which claims priority to U.S.Provisional Application No. 62/435,504 filed Dec. 16, 2016, and U.S.Provisional Application No. 62/437,372 filed Dec. 21, 2016, each ofwhich is incorporated by reference in its entirety herein.

FIELD OF THE INVENTION

The present invention relates to biocidal compositions, particularlywood preservative compositions comprising one or more copper compoundsand penflufen. More particularly, the invention relates to a method ofmanufacture of particulate-based biocidal compositions capable of beinginjected into wood, the biocidal compositions, methods of preservingwood using the compositions, and wood treated with the compositions ofthis invention.

BACKGROUND OF THE INVENTION

Copper compounds are common biocides for the protection of wood or woodproducts from fungal decay. Compositions comprising copper compoundsalone, however, cannot be used as wood preservative treatments becausethe presence of copper-tolerant fungi in wood prevents such compositionsfrom being effective.

The prior art discloses a variety of pyrazole-based organic biocides.For example, in U.S. patent application Ser. No. 13/880,619, Pub. No.US2014/0079806, penflufen was disclosed as a fungicide for the treatmentof wood against basidiomycetes. However, some fungi are tolerant ofpyrazole fungicides.

Different approaches to the problem of fungal tolerance have beenreported. For example, in U.S. patent application Ser. No. 13/880,985,Pub. No. US2014/0088041, penflufen mixtures were disclosed as fungicidesfor the protection of industrial materials. In U.S. patent applicationSer. No. 15/177,845, Pub. No. US2016/0295863, penflufen mixtures werealso disclosed as fungicides for the protection of industrial materials.

The inventors have surprisingly discovered that wood preservativecompositions comprising particles of one or more copper compound andpenflufen effectively prevent fungal decay in treated wood or woodproducts. Also surprisingly, the inventors have discovered that the woodpreservative compositions comprising one or more copper compounds andpenflufen exhibit a synergistic effect in resisting decay of sapwoodspecies of wood by brown rot fungi.

The inventors have also surprisingly discovered a method of making woodpreservative compositions comprising micronized particles of one or morecopper compounds and penflufen. Compositions comprising micronizedparticles frequently suffer from aggregation or other morphologicalinstability, but the wood preservative compositions produced accordingto the present invention are surprisingly stable under storageconditions.

SUMMARY OF THE INVENTION

When either a copper compound or a pyrazole fungicide is used alone as awood preservative composition, only certain wood decay fungi may becontrolled. It was surprisingly found that a copper compound incombination with penflufen provided synergistic, broad spectrum control.

In certain embodiments, the invention is directed to methods of treatingwood or a wood product comprising a step of contacting the wood or woodproduct with an aqueous wood preservative composition, which exhibits asynergistic effect in resisting fungal decay. The aqueous woodpreservative composition itself comprises an aqueous carrier, a coppercompound and penflufen in a copper:penflufen ratio of between about 1:1to about 500:1. In other embodiments, the invention is directed to thewood preservative composition itself.

In certain embodiments, the aqueous wood preservative compositioncomprises a micronized copper compound. In a preferred embodiment, themicronized copper compound has a particle size of 5 to 5000 nanometers.

In certain embodiments, the aqueous wood preservative compositioncomprises penflufen. In a preferred embodiment, penflufen is in amicronized form and the micronized penflufen has a particle size of 5 to5000 nanometers. In another preferred embodiment, penflufen is eithersolubilized, emulsified or encapsulated in a polymer matrix.

In certain embodiments, the aqueous wood preservative compositioncomprises both a micronized copper compound and penflufen. In oneembodiment, the aqueous wood preservative composition comprises both amicronized copper compound and emulsified penflufen. In anotherembodiment, the aqueous wood preservative composition comprises both amicronized copper compound and micronized penflufen. In a preferredembodiment, the micronized copper compound and/or the micronizedpenflufen has a particle size of 5 to 5000 nanometers. In anotherpreferred embodiment, the particle size of the micronized coppercompound and/or the micronized penflufen varies by less than 50nanometers after storage from week one to 6 months at 24° C. In anotherpreferred embodiment, the present wood preservative composition canfurther be used in combination with other known preservative chemicals,including boron based preservatives, such as boric acid, sodium salt ofborates; triazole compounds, pentachlorophenol, and sodium fluoride.Triazoles of the wood preservative formulations of the inventioninclude, but are not limited to epoxiconazole, triadimenol,propiconazole, prothioconazole, metconazole, cyproconazole,tebuconazole, flusilazole, paclobutrazol, fluconazole, isavuconazole,itraconazole, voriconazole, pramiconazole, ravuconazole, andposaconazole.

In certain embodiments, the aqueous wood preservative compositioncomprises a solubilized copper compound. In other embodiments, theaqueous wood preservative composition used in the claimed method oftreating wood or a wood product comprises emulsified penflufen orsoluble penflufen. In another preferred embodiment, the presentcomposition can further comprise a boron compound, such as boric acid,sodium salt of borates; a triazole compound, or pentachlorophenol.Triazoles of the wood preservative formulations of the inventioninclude, but are not limited to epoxiconazole, triadimenol,propiconazole, prothioconazole, metconazole, cyproconazole,tebuconazole, flusilazole, paclobutrazol, fluconazole, isavuconazole,itraconazole, voriconazole, pramiconazole, ravuconazole, andposaconazole.

In certain embodiments, the invention is direct to methods of treatingwood or a wood product comprising a step of contacting the wood or woodproduct with an aqueous wood preservative composition, as describedabove. The treated wood or wood product in this embodiment retainspenflufen in an amount between about 4 to 200 g/m³. In a preferredembodiment, the treated wood or wood product in this embodiment retainspenflufen in an amount between about 8 to 100 g/m³ and in a morepreferred embodiment in an amount between about 8 to 80 g/m³.

In certain embodiments, the aqueous wood preservative composition,applied to achieve a retention in an amount between about 4 to 200 g/m³,resists decay of sapwood species of wood by brown rot fungi in asoil-block test according to American Wood Protection AssociationStandard E10-2015, such that the treated wood or wood product losesbetween less than 2% and 20% mean weight. In certain embodiments, thebrown rot fungi are selected from the group consisting of Gloeophyllumtrabeum, Fibroporia radiculosa, Postia placenta and Coniophora Postiaputeana. In certain embodiments, the sapwood species is southern yellowpine.

In certain embodiments, the invention is directed to wood or a woodproduct comprising a copper compound and penflufen, wherein thecopper:penflufen ratio is between about 1:1 to about 500:1 and whereinthe wood or wood product contains the penflufen in an amount betweenabout 4 to 200 g/m³. In a preferred embodiment, the invention isdirected to wood or a wood product comprising a copper compound andpenflufen, wherein the copper:penflufen ratio is between about 1:1 toabout 500:1 and wherein the wood or wood product contains the penflufenin an amount between about 8 to 80 g/m³.

A stable micronized penflufen particle dispersion may be preparedthrough a milling process. In one embodiment, the milling processcomprises the step of mixing a slurry of penflufen and dispersantmixture in a solvent, and wet milling of the slurry with a high densitygrinding media having a diameter between 0.05 mm and 1.0 mm, preferablybetween 0.1 mm to 0.5 mm, and a density of 2.5 g/cc or higher,preferably 3.5 g/cc or higher. The milled penflufen dispersion has aparticle size in the range of 5 nanometers to 5000 nanometers (5microns), specifically with a size of d95 of about 5 microns or less anda d50 of greater than 20 nanometers (0.02 microns).

In certain embodiments, the dispersant used in the milling is apolymeric dispersant. In a preferred embodiment, the dispersant is asalt of naphthalene sulfonate condensate, or a salt of sulfonatednaphthaleneformaldehyde condensate, or sulfonated naphthaleneformaldehyde polymer admixture. In certain embodiments, the weight ratioof the penflufen to the dispersant varies from 1:10 to about 1000:1, andpreferred ratio is about 1:1 to about 100:1.

The prepared micronized penflufen compositions are stable underhigh-shear mixing and subject to multiple pressure treatments. Inaddition, the milled penflufen particles can be mixed with compositionscontaining copper compounds and the mixture of penflufen/copper is alsostable under high shear mixing and subject to multiple pressuretreatment. Upon storage, the mean particle size, the d95 and the d50 ofthe prepared penflufen compositions remain stable from the first monthto the sixth month.

DETAILED DESCRIPTION OF THE INVENTION

Unless otherwise specified, all compositions are given in “percent”,where the percent is the percent by weight based on the total weight ofthe entire component, e.g., of the particle, or to the injectablecomposition. In the event a composition is defined in “parts” of variouscomponents, this is parts by weight wherein the total number of parts inthe composition is between 90 and 110.

As used herein, the term “resistant to fungal decay” indicates that thewood or wood product is suitable for use in residential constructionunder relevant building codes. As used herein, the term “stable” used inreference to a wood preservative composition means that wood can bepressure treated with the “stable” composition without fallout on thesurface of the wood.

As used herein, the term “micronized” refers to particulate materialthat has been milled to a relatively small particle size. Thus, amicronized compound is also a dispersed or particulate compound. Theterm “micronized” is not intended to indicate a specific particle sizeor range of particle sizes, although the micronized particles of thepresent invention tend to have particle sizes less than 10 μm indiameter.

As used herein, particle diameters may be expressed as “d_(xx)” wherethe “xx” is the weight percent (or alternately the volume percent) ofthat component having a diameter equal to or less than the d_(xx). Thed₅₀ is the diameter where 50% by weight of the component is in particleshaving diameters equal to or lower than the d₅₀, while just under 50% ofthe weight of the component is present in particles having a diametergreater than the d₅₀. Particle diameter is preferably determined byStokes Law settling velocities of particles in a fluid, for example witha Model LA 700 or a CAPA™ 700 sold by Horiba and Co. Ltd., or aSedigraph™ 5100T manufactured by Micromeritics, Inc., which uses x-raydetection and bases calculations of size on Stoke's Law, to a size downto about 0.2 microns. Smaller sizes are preferably determined by adynamic light scattering method, preferably with a Coulter™ counter.

Generally, the copper or copper compounds of the present invention areprepared from: but are not limited to copper metal, cuprous oxide (asource of copper (I) ions), cupric oxide (a source of copper (II) ions),copper hydroxide, copper carbonate, basic copper carbonate, copperoxychloride, copper 8-hydroxyquinolate, copper dimethyldithiocarbamate,copper omadine, copper borate or basic copper borates, copper residues(copper metal byproducts) or any suitable copper source. Coppercompounds disclosed in the current invention can be either particulatecopper dispersion or soluble copper solution. In the case of particulatecopper dispersion, copper compounds are dispersed with an aid ofpolymeric dispersant(s). In the case of soluble copper solution, coppercompounds may be solubilized by contacting them with a solubilizingagent. Examples of solubilizing agents include, but are not limited to,alkanolamines, such as, for example, monoethanolamine, ethanolamine,diethanolamine, triethanolamine and ammonia. In one embodiment, coppercompounds are prepared in a micronized dispersion.

In another embodiment, the particles comprise at least about 20%, 30%,40%, 50%, 60%, 70% or 75% of the weight of the any of these coppercompounds. The most preferred copper compounds are copper hydroxide andbasis copper carbonate.

In certain embodiments, the aqueous wood preservative compositioncomprises one or more copper compound and penflufen, where the coppercompound can be either micronized or amine solubilized. In oneembodiment, the aqueous wood preservative composition comprises asolubilized copper compound and emulsified penflufen. In anotherembodiment, the aqueous wood preservative composition comprises amicronized copper compound and emulsified penflufen. In anotherembodiment, the aqueous wood preservative composition comprises both amicronized copper compound and micronized penflufen. In a preferredembodiment, the micronized copper compound and/or the micronizedpenflufen has a particle size of 5 to 5000 nanometers. In anotherembodiment, wood or a wood product is impregnated with dispersedparticles of one or more copper compounds and dispersed penflufenparticles, which comprise the biocidal compositions of the invention.

In one embodiment, the dispersants used in the wood-preservativecompositions of the present invention include, but are not limited tocationic, non-ionic or anionic dispersants, acrylic copolymers, anaqueous solution of copolymers with pigment affinity groups,polycarboxylate ethers, modified polyacrylates, acrylic polymeremulsions, modified acrylic polymers, poly carboxylic acid polymers andtheir salts, modified poly carboxylic acid polymers and their salts,fatty acid modified polyesters, aliphatic polyethers or modifiedaliphatic polyethers, polyetherphosphates, solution of polycarboxylateethers, sodium polyacrylates, sodium polymethacrylates, modifiedpolyether or polyester with pigment affinity groups, fatty acidderivatives, urethane copolymers or modified urethane copolymers,acrylic acid/maleic acid copolymers, polyvinyl pyrrolidones or modifiedpolyvinyl pyrrolidones, modified maleic anhydride/styrene copolymers,lignins and the like.

Preferably, the dispersants used in the wood-preservative compositionsof the present invention are polymeric dispersants. In one embodiment,the polymeric dispersants contain at least one pigment affinity groupcapable of binding to a solid particle. In another embodiment, thepolymeric dispersants stabilize a solid particle. Preferably, thepolymeric dispersants used in the wood-preservative compositions of thepresent invention are modified polycarboxylate ethers, modified polycarboxylic acid polymers and their salts, solutions of polycarboxylateethers and modified polyethers or polyesters with pigment affinitygroups.

In a first embodiment of the invention, the dispersant is a non-ionicsurfactant. Non-ionic surfactants are materials which carry no discretecharge when dissolved or suspended in aqueous media. The hydrophilicityof the surfactant is provided by hydrogen bonding with water molecules.Oxygen atoms and hydroxyl groups readily form strong hydrogen bonds.Such hydrogen bonding can provide a dispersion (suspensibility) orsolubilization of the fungicide in neutral or alkaline media. Non-ionicmaterials useful for the present invention further include polyalkyleneoxide block copolymers. Such block copolymers typically have at leastone block segment comprising -(AO)_(x)-, wherein AO represents anoxyalkylene moiety and x is a number of about 1 to about 100.Preferably, AO represents either an ethylene oxide moiety or a propyleneoxide moiety. The -(AO)_(x)-block must be attached to a functional groupdiffering in hydrophilicity (or hydrophobicity).

Exemplary surfactants/dispersants include ethoxylates of castor oil(ethyleneoxide degree of polymerization 30 60 ethoxy moieties);ethoxylates of tridecylalcohol(ethyleneoxide degree of polymerization 420); ethoxylates of a C10 C14 alcohol (ethyleneoxide degree ofpolymerization 4 20); ethoxylates of nonylphenol (ethyleneoxide degreeof polymerization 6 50); ethoxylates of a fatty alcohol (ethyleneoxidedegree of polymerization 3 20); ethoxylates of a sorbitol ester(ethyleneoxide degree of polymerization 10 40); ethoxylates of asorbitan-tallate (ethyleneoxide degree of polymerization 10 40);ethoxylates of a tristyrphenol (ethyleneoxide degree of polymerization 320); ethoxylates of a isodecyl alcohol (ethyleneoxide degree ofpolymerization 3 10); ethoxylates of a isododecyl alcohol (ethyleneoxidedegree of polymerization 3 10), or mixtures thereof

A group of non-ionic surfactants useful in the context of the presentinvention includes a polycondensation product containing an alkyleneglycol as a monomer. Exemplary compounds include a polyethylene glycol,a polypropylene glycol or a block polymer of ethylene glycol andpropylene glycol. The degree of polymerization of these compounds ispreferably in the range of about 5 to about 1,000, and more preferablyin the range of from about 10 to about 500.

Non-ionic dispersants further include polyalkylene oxide blockcopolymers. Such block copolymers typically have at least one blocksegment comprising -(AO)_(x)-, wherein AO represents an oxyalkylenemoiety and x is a number of about 1 to about 100. Preferably, AOrepresents either an ethylene oxide moiety or a propylene oxide moiety.The -(AO)_(x)- block must be attached to a functional group differing inhydrophilicity (or hydrophobicity). Such copolymers can be derived fromhigher alkylene oxides such as ethylene oxide, propylene oxide, butyleneoxide, styrene oxide, etc. Such block copolymers typically contain apolyethylene oxide block which is relatively hydrophilic combined withanother polyalkylene oxide block which is typically hydrophobicresulting in surfactant properties. Another non-ionic surfactantincludes polyoxypropylene-polyoxyethylene block copolymer surfactants.Those surfactants comprising a center block of polyoxypropylene units(PO), and having a block of polyoxyethylene (EO) units to each side ofthe center PO block, are generally useful in the context of thisinvention, particularly where the average molecular weight ranges fromabout 900 to 14,000, and the percent of weight EO ranges from about 10to 80. These types of surfactants are sold commercially as “Pluronics.”

A second, and preferred, group of non-ionic surfactants useful in thecontext of the present invention includes etherified compound of thefirst group of compounds and an aliphatic alcohol. In such a manner, adispersant having a polyethylene oxide block which is relativelyhydrophilic combined with a long alkyl section, e.g., C₆ to C₃₀, whichis typically hydrophobic can be obtained, resulting in surfactantproperties. Exemplary compounds include polyethylene glycol oleyl ether(ethyleneoxide degree of polymerization 4 to 50), polyethylene glycolcetyl ether (ethyleneoxide degree of polymerization 4 to 50),polyethylene glycol stearyl ether (ethyleneoxide degree ofpolymerization 4 to 50), polyethylene glycol lauryl ether (ethyleneoxidedegree of polymerization 4 to 50), polyethylene glycol tridecyl ether(ethyleneoxide degree of polymerization 4 to 50), polyethylene glycolnonylphenyl ether (ethyleneoxide degree of polymerization 4 to 50),polyethylene glycol octylphenyl ether (ethyleneoxide degree ofpolymerization 4 to 50), and the like. A preferred degree ofpolymerization for compounds in this class is in the range of from 4 to20, for example between about 6 to about 12.

A subgroup of compounds is an etherified compound of the above-mentionedgroup of compounds and a higher fatty acid. Exemplary compounds includepolyethylene glycol monolaurate (ethyleneoxide degree of polymerization2 to 50), polyethylene glycol monostearate (ethyleneoxide degree ofpolymerization 2 to 50), polyethylene glycol monooleate (ethyleneoxidedegree of polymerization 2 to 50), and the like.

Other non-ionic surfactants include polyoxypropylene-polyoxyethyleneblock copolymer surfactants. Those surfactants comprising a center blockof polyoxypropylene units (PO), and having a block of polyoxyethylene(EO) units to each side of the center PO block, are generally useful inthe context of this invention, particularly where the average molecularweight ranges from about 900 to 14,000, and the percent of weight EOranges from about 10 to 80.

In addition, hydrophobically modified pluronic surfactants can beemployed, wherein a modifying group (R) such as a methyl, ethyl, propyl,butyl, benzyl, etc. may be capping the terminal oxy alkaline group;e.g., R-(EO)_(n)-(PO)_(m)-(EO)_(n)-R.

Exemplary dispersants include linear alcohol alkoxylates, such as thelinear alcohol ethoxylates or an ethyoxylated/propoxylated block. Ifdesired, the alcohol alkoxylate is suitably end-capped with a loweralkyl group, and such a product is commercially available asPOLY-TERGENT SLF-18 surfactant, available from BASF Corporation. Otheruseful anionics are polycarboxylated alcohol alkoxylates, preferablythose selected from the group consisting of the acids or organic orinorganic salts of the following: polycarboxylated linear alcoholalkoxylates, polycarboxylated branched alcohol alkoxylates,polycarboxylated cyclic alcohol alkoxylates, and combinations thereof.Nonionic surfactants include, for example: alkylphenol ethoxylates, forexample, ethoxylated nonyl phenol, alkylphenol ethoxylate or nonylphenolethoxylate containing from about 1 to about 20 or more moles of ethyleneoxide per mole of phenol.

A preferred group of compounds includes phosphate (or less preferablysulfate or sulfonate) ester of any of the above-mentioned groups ofcompounds. Exemplary compounds include polyethylene glycol oleyl etherphosphate (ethyleneoxide degree of polymerization 4 to 50), polyethyleneglycol cetyl ether phosphate (ethyleneoxide degree of polymerization 4to 50), polyethylene glycol stearyl ether phosphate (ethyleneoxidedegree of polymerization 4 to 50), polyethylene glycol lauryl etherphosphate (ethyleneoxide degree of polymerization 4 to 50), polyethyleneglycol tridecyl ether phosphate (ethyleneoxide degree of polymerization4 to 50), polyethylene glycol nonylphenyl ether phosphate (ethyleneoxidedegree of polymerization 4 to 50), polyethylene glycol octylphenyl etherphosphate (ethyleneoxide degree of polymerization 4 to 50), and thelike.

In certain embodiment, the dispersant to copper and/or penflufen ratiovaries from about 1:500 to about 1000:1. The preferred dispersant tocopper and/or penflufen ratio is about 1:100 to about 10:1, and the mostpreferred ratio about 5:100 to 1:1.

Leaching is a function of particle size and the solubility of thematerial. Larger size particles have lower leach rates, while particlesin a size range from 1 to 10 nanometers under certain circumstances willnot have a leach rate much different than that of an injected and driedcopper salt solution. In preferred embodiments of this invention, thed₅₀ is at least 0.04 microns, meaning at least 50% by weight of theparticulates have a size greater than 40 nanometers. In more preferredembodiments, the d₅₀ is 0.10 microns or greater. In one preferredembodiment, at least 80% by weight of the particulates have a sizebetween 0.05 microns and 1.0 microns.

Leaching is not the only mechanism whereby material can be flushed fromwood. Because the material is in particulate form, there is apossibility that particulates will be flushed from the wood during thefinal vacuum process. Evidence suggests that very small substantiallyspherical nanoparticles, i.e., spherical particles of size 5 to 20nanometers, can migrate freely through a wood matrix. However, whilesaid particles are easy to inject, they are also clearly easilytransported through wood and would be easily flushed from the woodduring the final vacuum stage of vacuum/pressure impregnation process.Therefore, in preferred embodiments of the invention the material issubstantially free of substantially spherical particulates, wherein theparticle diameter is less than about 20 nanometers, particularly lessthan 15 nanometers. By substantially free we mean the d₂₀ is greaterthan 0.02 microns.

Another key aspect of the invention is to make a variety of biocidalparticulate slurry compositions available that are injectable into wood,thereby serving as a particulate wood preservative. Requirements ofinjectability into wood for substantially round, e.g., the diameter inone direction is within a factor of two of the diameter measured in adifferent direction, such as would be found in milled particles, are:

1) the d₉₆ is equal to or less than about 1 micron, but is preferablyabout 0.7 microns or less, more preferably about 0.5 microns or less,for example equal to or less than about 0.3 microns, or equal to or lessthan about 0.2 microns;

2) the d₉₉ is equal to or less than about 2 microns, preferably equal toor less than 1.5 microns, more preferably equal to or less than about 1micron; and 3) the d₅₀ is less than 0.5 microns, preferably less than0.4 microns, and the d₅₀ is greater than 0.02 microns, more preferablygreater than 0.05 microns, for example a slurry composition where thed₅₀ is between about 0.1 microns and about 0.3 microns. We believe thefirst criteria primarily addresses the phenomena of bridging andsubsequent plugging of pore throats, the second criteria addresses thephenomena of forming a filter cake, and the third criteria addresses theissue of having particulates disposed in the wood which have an optimumsize to ensure the treatment has an acceptable bio-activity andlifetime. Once a pore throat is partially plugged, complete plugging andundesired buildup generally quickly ensues.

However, there are minimum preferred particulate diameters for the woodtreatment, which depend somewhat on the compound(s) that are in theparticulates. If a copper compound has a high solubility, very smallparticulates having a large surface to mass ratio will result in toohigh a copper ion concentration, and too fast a copper leaching,compared to preferred embodiments of this invention. Generally, it ispreferred that for particulate copper compounds, the d₂₀ be above 0.01microns in diameter, preferably greater than 0.03 microns, for examplegreater than 0.06 microns in diameter. While penflufen particles can besmaller, as these compounds generally exhibit lower solubility in waterthan do the copper compounds, nevertheless a preferred minimum d20 for amixture of particulate copper compounds and particulate penflufen is0.01 microns.

Preferred particles comprise at least 30%, preferably at least 50%, morepreferably at least 70%, for example between about 80% and about 98% byweight of total of copper hydroxides, copper(I) oxide, basic coppercarbonates, copper carbonates, copper oxychloride, basic copperphosphate, basic copper phosphosulfate, tribasic copper sulfate,alkaline copper nitrate, basic copper borate, copper silicate, ormixtures thereof. The various particles within a wood preservative cancomprise different biocides, even different copper compounds. Forexample, a treatment may contain particles that comprise copper borateor copper borate in combination with copper hydroxide and/or a basiccopper salt, particularly basic copper carbonate, other particles thatcomprise basic copper carbonate, optionally particles that comprisebasic copper phosphate, and even other particles that comprise copperoxide. The particles having different phases may in preferredembodiments be of different sizes, depending on the copper materialpresent.

In one embodiment, exemplary wood preservatives have a d₅₀ equal to orsmaller than 0.5 μm, 0.25 μm, 0.2 μm, or 0.15 μm. Advantageously, thed₉₆, and preferably the d₉₉, are within a factor of three of the d₅₀,and very preferably is less than 1.2 microns. In one embodiment, the d₅₀is at least 25 nanometers, for example, at least 50 nanometers.

There is a large number of references describing how to makecopper-containing “nanoparticles.” These references generally cannot beused to manufacture the particulates at the desired cost. One methodthat is particularly not cost effective is using an emulsionprecipitation or emulsion crystallization technique, where smallparticles are allowed to grow in a certain phase of an emulsion, wherethe ultimate size of the particle is limited by the amount of acomponent in a droplet in the emulsion. Both inorganic salts and organicbiocidal particulates can be formed in this manner, but not at a costwhere such materials would be useful for foliar applications on cropsnor for wood preservation.

U.S. Pat. No. 4,808,406, the disclosure of which is incorporated byreference, describes a useful method for producing finely divided stablecupric hydroxide composition of low bulk density comprising contactingsolutions of an alkali metal carbonate or bicarbonate and a copper salt,precipitating a basic copper carbonate-basic copper sulfate to a minimumpH in the range of greater than 5 to about 6, contacting the precipitatewith an alkali metal hydroxide and converting basic copper sulfate tocupric hydroxide. Another method of manufacturing the copper compoundsis the method described in U.S. Pat. No. 4,404,169, the disclosure ofwhich is incorporated by reference. This patent describes a process ofproducing cupric hydroxides having stability in storage if phosphateions are added to a suspension of copper oxychloride in an aqueousphase. The copper oxychloride is then reacted with alkali metalhydroxide or alkaline earth metal hydroxide, and the cupric hydroxideprecipitated as a result of the suspension is washed and thenre-suspended and subsequently stabilized by the addition of acidphosphate to adjust a pH value of 7.5 to 9. The suspended copperoxychloride is preferably reacted in the presence of phosphate ions inan amount of 1 to 4 grams per liter of the suspension and at atemperature of 20° to 25° C. and the resulting cupric hydroxide isstabilized with phosphate ions.

Wet ball milling, with milling media of specified characteristics, canadvantageously modify particle size and morphology of copper compoundsand even solid organic biocides known to be highly resistant to milling,such as chlorothalonil and penflufen, to a size where the compounds arereadily injectable into wood. Surprisingly, it has been found that bothorganic and inorganic particulates can be readily milled into aninjectable material by wet milling with a milling material such as a 0.3to a 0.7 mm milling media having density greater than 3 grams/cm³, forexample equal to or greater than 3.8 grams/cm³ such as 0.5 mm diameterzirconium silicate, preferably greater than 5.5, grams/cm³ provided by a0.5 mm milling bead of zirconium oxide which may contain one or moredopants such as cerium and/or yttrium, and/or magnesia in a stabilizingamount. Additionally, regardless of the particle size of the feedstock,the particles can be broken down to injectable size in a matter ofminutes to at most a few hours. Beneficially all injectable formulationsfor wood treatment should be wet-milled, even when the “mean particlesize” is well within the range considered to be injectable into wood.

The milling media, also called grinding media or milling beads, iscentral to this invention. The selection of milling media is expresslynot a routine optimization. The use of this media allows an averageparticle size and a narrow particle size distribution that hadpreviously not been obtainable in the art, nor did the results in theprior art allow one to predict the unexpected results we obtained. Amajor contribution of this invention is a method of preparing aparticulate biocide product having a d₅₀ equal to or less than about 1micron, comprising the steps of: 1) providing the solid inorganic ororganic biocide, and a liquid comprising a surface active agent, to amill; providing a milling media comprising an effective amount ofmilling beads having a diameter between 0.01 mm and 0.8 mm, preferablybetween about 0.1 mm and about 0.7 mm, more preferably between about 0.1mm and about 0.5 mm, wherein these milling beads have a density greaterthan about 2.5 grams/cm³, preferably equal to or greater than 3.5grams/cm³, more preferably equal to or greater than 3.8 grams/cm³, mostpreferably equal to or greater than 5.5 grams/cm³, for example azirconia bead having a density of about 6 grams/cm³; and 2) wet millingthe material at high speed, for example between 300 and 6000 rpm, morepreferably between 1000 and 4000 rpm, for example between about 2000 and3600 rpm, where milling speed is provided for a laboratory scale ballmill, for a time sufficient to obtain a product having a mean volumeparticle diameter of about 1 micron or smaller, for example betweenabout 5 minutes and 300 minutes, preferably from about 10 minutes toabout 240 minutes, and most preferably from about 15 minutes to about 60minutes. As little as 5% by volume of the milling media need be withinthe preferred specifications for milling some materials, but betterresults are obtained if greater than 10% by weight, preferably greaterthan 25% by weight, for example between 40% and 100% by weight of themilling material is within the preferred specifications. For millingmaterial outside the preferred specifications, advantageously thismaterial has a density greater than 3 grams/cm³ and a diameter less than4 mm, for example 1 or 2 mm zirconia or zircionium silicate millingbeads.

The milling media advantageously comprises or consists essentially of azirconium-based material. The preferred media is zirconia (density ˜6g/cm³), which includes preferred variants such as yttria stabilizedtetragonal zirconium oxide, magnesia stabilized zirconium oxide, andcerium doped zirconium oxide. For some biocides, zirconium silicate(density ˜3.8 g/cm³) is useful. However, for several biocides such aschlorothalonil, zirconium silicate will not achieve the required actionneeded to obtain the narrow sub-micron range of particle sizes inseveral preferred embodiments of this invention. In an alternateembodiment, at least a portion of the milling media comprises orconsists essentially of metallic material, e.g., steel. The millingmedium is a material having a density greater than about 2.5, preferablyat least about 3.8, more preferably greater than about 5.5, for exampleat least about 6 g/cm³.

We believe that density and particle size are the two most importantparameters in the milling media. Preferably the milling media comprisesor consists essentially of particles, having a size (diameter) betweenabout 0.01 mm and about 0.8 mm, preferably between about 0.1 mm andabout 0.7 mm, for example between about 0.1 mm and 0.5 mm. Alsopreferably, the milling media can have a density greater than about 3.5g/cm³, preferably greater than about 5.5 g/cm³, more preferably greaterthan about 6 g/cm³. The zirconium-based milling media useful in thepresent invention can comprise or consist essentially of particleshaving a diameter (as the term is used in the art) between about 0.1 mmand about 0.8 mm, preferably between about 0.1 mm and about 0.7 mm, forexample between about 0.1 mm and 0.5 mm.

Not all the milling media need be the preferred material, e.g., having apreferred diameter between 0.1 mm and 0.8 mm, preferably between 0.1 mmand 0.7 mm, more preferably between 0.1 mm and 0.5 mm, and having apreferred density equal to or greater than 3.5 grams/cm³, preferablygreater than or equal to 5.5 grams/cm³, more preferably greater than orequal to 6 grams/cm³. In fact, as little as 10% of this media willprovide the effective grinding. The amount of the preferred millingmedia, based on the total weight of media in the mill, can be between 5%and 100%, is advantageously between 10% and 100%, and is preferablybetween 25% and 90%, for example between about 40% and 80%. Media notwithin the preferred category can be somewhat larger, say 1 mm to 4 mmin diameter, preferably from 1 mm to 2 mm in diameter, andadvantageously also has a density equal to or greater than 3.5grams/cm³.

A first aspect of the invention is a method of preparing a micronizedbiocide product, e.g., penflufen comprising the steps of: 1) providingthe solid biocide in particle form to a ball mill, providing a liquid toa mill, and providing a milling media to the mill, wherein the millingmedia comprises at least 5%, preferably at least 10%, more preferably atleast 25% by weight of the milling media having a particle diameterbetween 0.1 to 0.8 mm, preferably between 0.1 and 0.5 mm, and having adensity equal to or greater than 3.5 g/cm³, preferably equal to orgreater than 5.5 g/cm³; and 2) milling the material for a timesufficient to obtain a product having a mean volume particle diameterd₅₀ of about 1 micron or smaller. The mill speed is advantageously fast,for example from 1000 rpm to about 4000 rpm, and the milling time ispreferably between 10 minutes and 240 minutes.

Generally, less dense milling media will provide a relatively largerd₅₀, which can be useful for foliar applications. The denser millingmedia, for example media having a density greater than 5.5 g/cm³,provides a smaller d₅₀. Surprisingly, varying the milling time has verylittle effect on the d₅₀. The preferred dense milling media is zirconiaor cerium doped zirconia. The zirconium oxide can comprise anystabilizers and/or dopants known in the art, including, for example,cerium, yttrium, and magnesium. An alternate useful dense millingmaterial is steel. Generally, at least 25% by weight of the millingmedia must have a density greater than 3.8 and a diameter between 0.1and 0.7 mm to reliably obtain injectable particulate copper compounds.

Manufacturing injectable solid substantially insoluble organic biocideparticles, e.g., penflufen, can beneficially be performed by 1)providing the penflufen and a liquid comprising surface active agents toa mill, and 2) milling the material with a milling media having adensity greater than 2.5 grams/cm³, for example milling beads comprisinga zirconium oxide having a diameter between about 0.01 mm and about 0.5mm, and preferably a density greater than 3.5 g/cm³. The invention alsoencompasses an organic biocide particulate product, e.g., a penflufenproduct, having a d₅₀ below about 1 micron, typically below about 0.5microns, and preferably between 0.1 and 0.3 microns, whichadvantageously also exhibits a d₅₀ that is less than about three timesthe d₉₈ preferably less than about two times the d_(98.)

The attainment of the injectable size, which generally requires both ad₅₀ below 0.5 microns and a d₉₈ less than three times the d₅₀, was asurprising development. Milling copper compounds for several days with a2 mm milling media could not provide the required particle sizedistribution, even if the feed material had a d₅₀ of less than 0.3microns. Milling a milling-resistant organic biocide, such as penflufen,with 1 mm zirconia provided a penflufen product with a d₅₀ of 2 to 3microns. Yet, surprisingly, milling each of these with a preferredmilling media, e.g., zirconia-based milling beads having a diameterbetween 0.4 and 0.5 mm, provided each of these products in injectablesub-micron slurries in under a few hours, often in less than 30 minutes.

Advantageously, the liquid comprises one or more dispersants and/orstabilizers. The presence of these promotes a smaller d₅₀ and a narrowerparticle size distribution, because agglomeration of particulates isdiscouraged. Aqueous dispersing agents for such dispersed solids arewell known to those skilled in the art and include, but are not limitedto, nonionic surfactants such as ethylene oxide/propylene oxide blockcopolymers, polyvinyl alcohol/polyvinyl acetate copolymers, polymericnonionic surfactants such as the acrylic graft copolymers; anionicsurfactants such as polyacrylates, lignosulfonates, polystyrenesulfonates, maleic anhydride-methyl vinyl ether copolymers, naphthalenesulfonic acid formaldehyde condensates, phosphate ester surfactants suchas a tristyrenated phenol ethoxylate phosphate ester, maleicanhydride-diisobutylene copolymers, anionically modified polyvinylalcohol/polyvinylacetate copolymers, and ether sulfate surfactantsderived from the corresponding alkoxylated nonionic surfactants;cationic surfactants; zwitterionic surfactants; and the like.

Penflufen used in the present invention can be prepared in variety ofways. For example, as a solution in one or more organic solvents, anemulsion in water by emulsifying the compounds with the aid ofemulsifiers, or as dispersion in particulate form by dispersing throughhomogenizer or high speed agitation or through milling/grinding process,or an encapsulation embed in polymer matrix or any other chemical andphysical means. In one embodiment, penflufen is prepared as an emulsionconcentrate. When prepared as emulsion or emulsifiable concentrate,penflufen is dissolved in the mixture solvent(s) and emulsifiers orsurfactants. Non-limited examples of solvents include mineral oils,white spirits, dichloromethane, hexane, toluene, alcohols such asmethanol, ethanol, benzyl alcohol and 2-propanol, glycols such asethylene glycol and propylene glycol, ethers, esters, poly-glycols,poly-ethers, amides, methylene chloride, acetone, chloroform,N,N-dimethyl octanamide, N,N-dimethyl decanamide, N-methyl2-pyrrolidone, n-(n-octyl)-2-pyrrolidone, and combinations of the above.Emulsifiers can be anionic, cationic, or nonionic or the combinations.Examples of emulsifiers include, but are not limited to, ethyoxylatedalkylphenols or amines or amides or aryl phenols or fatty esters, fattyacids and derivatives, ethoxylated alcohols and derivatives, sulfonatedamine or amides and derivatives, carboxylated alcohol or alkylphenolethoxylates and derivatives, glycol ethers or esters. Additionalexamples of emulsifers can be found in McCutcheon's Emulsifiers andDetergents, 2016. In another embodiment, penflufen is prepared asmicroencapsulated particles. Microencapsulation of penflufen includesteps of preparation of solutions, homogenization and solventevaporation. When prepared as microencapsulation, penflufen is firstdissolved in a solvent(s) followed by addition of a polymer(s) oremulsifier. The mixture is then homogenized under high shear mixing, andthe solvent remained in the mixture is then evaporated off, and thefinal microencapsulation is formed. In a more preferred embodiment,penflufen is prepared as a micronized dispersion through millingprocess.

The milling of the organic biocides is advantageously performed in thepresence of an aqueous medium containing surfactants and/or dispersants,such as those known in the art. Use of other media, including forexample polar organic solvents such as alcohols, generally does notoffer added advantage sufficient to outweigh the cost and associatedhazards of milling with solvents. Because it is now possible to achievea smaller particle size and a narrower particle size distribution usingthe present invention than was previously known in the art, the numberand amount of stabilizers and/or dispersants are less critical. As usedherein, the term “surface active agent” includes both singular andplural forms and encompasses generally both stabilizers and dispersants.The surface active agent may be anionic, cationic, zwitterionic, ornonionic, or a combination thereof. Generally, higher concentrations ofsurface active agents present during milling result in a smallerparticle size.

Examples of other suitable classes of surface active agents include, butare not limited to, anionics such as alkali metal fatty acid salts,including alkali metal oleates and stearates; alkali metal laurylsulfates; alkali metal salts of diisooctyl sulfosuccinate; alkyl arylsulfates or sulfonates, lignosulfonates, alkali metal alkylbenzenesulfonates such as dodecylbenzene sulfonate, alkali metal soaps,oil-soluble (e.g., calcium, ammonium, etc.) salts of alkyl aryl sulfonicacids, oil soluble salts of sulfated polyglycol ethers, salts of theethers of sulfosuccinic acid, and half esters thereof with nonionicsurfactants and appropriate salts of phosphated polyglycol ethers;cationics such as long chain alkyl quaternary ammonium surfactantsincluding cetyl trimethyl ammonium bromide, as well as fatty amines;nonionics such as ethoxylated derivatives of fatty alcohols, alkylphenols, polyalkylene glycol ethers and condensation products of alkylphenols, amines, fatty acids, fatty esters, mono-, di-, ortriglycerides, various block copolymeric surfactants derived fromalkylene oxides such as ethylene oxide/propylene oxide (e.g., PLURONIC™,which is a class of nonionic PEO-PPO co-polymer surfactant commerciallyavailable from BASF), aliphatic amines or fatty acids with ethyleneoxides and/or propylene oxides such as the ethoxylated alkyl phenols orethoxylated aryl or polyaryl phenols, carboxylic esters solubilized witha polyol or polyvinyl alcohol/polyvinyl acetate copolymers, polyvinylalcohol, polyvinyl pyrrolidinones (including those sold under thetradenames AGRIMER™ and GANEX™), cellulose derivatives such ashydroxymethyl cellulose (including those commercially available from DowChemical Company as METHOCEL™), and acrylic acid graft copolymers;zwitterionics; and the like; and mixtures, reaction products, and/orcopolymers thereof.

Additionally or alternatively, the surface active agent may include, butis not limited to, low molecular weight sodium lauryl sulfates, calciumdodecyl benzene sulfonates, tristyryl ethoxylated phosphoric acid orsalts, methyl vinyl ether-maleic acid half-ester (at least partiallyneutralized), beeswax, water soluble polyacrylates with at least 10%acrylic acids/salts, or the like, or a combination thereof.

Additionally or alternatively, the surface active agent may include, butis not limited to, alkyl grafted PVP copolymers commercially availableas GANEX™ and/or the AGRIMER™ AL or WP series, PVP-vinyl acetatecopolymers commercially available as the AGRIMER™ VA series, ligninsulfonate commercially available as REAX 85A (e.g., with a molecularweight of about 10,000), tristyryl phenyl ethoxylated phosphoricacid/salt commercially available as SOPROPHOR™ 3D33, GEROPON™ SS 075,calcium dodecylbenzene sulfonate commercially available as NINATE™ 401A, IGEPAL™ CO 630, other oligomeric/polymeric sulfonated surfactantssuch as Polyfon H (molecular weight ˜4300, sulfonation index ˜0.7, saltcontent ˜4%), Polyfon T (molecular weight ˜2900, sulfonation index ˜2.0,salt content ˜8.6%), Polyfon O (molecular weight ˜2400, sulfonationindex ˜1.2, salt content ˜5%), Polyfon F (molecular weight ˜2900,sulfonation index ˜3.3, salt content ˜12.7%), Reax 88B (molecular weight˜3100, sulfonation index ˜2.9, salt content ˜8.6%), Reax 100 M(molecular weight ˜2000, sulfonation index ˜3.4, salt content ˜6.5%),and Reax 825 E (molecular weight ˜3700, sulfonation index ˜3.4, saltcontent ˜5.4%), and the like.

Other notable surface active agents can include nonionic polyalkyleneglycol alkyd compounds prepared by reaction of polyalkylene glycolsand/or polyols with (poly)carboxylic acids or anhydrides; A-B-Ablock-type surfactants such as those produced from the esterification ofpoly(12-hydroxystearic acid) with polyalkylene glycols; high molecularweight esters of natural vegetable oils such as the alkyl esters ofoleic acid and polyesters of polyfunctional alcohols; a high molecularweight (MW>2000) salt of a naphthalene sulfonic acid formaldehydecondensate, such as GALORYL™ DT 120L available from Nufarm; MORWET EFW™available from Akzo Nobel; various Agrimer™ dispersants available fromInternational Specialties Inc.; and a nonionic PEO-PPO-PEO triblockco-polymer surfactant commercially available as PLURONIC™ from BASF.

Other examples of commercially available surface active agents includeAtlox 4991 and 4913 surfactants (Uniqema), Morwet D425 surfactant(Witco), Pluronic P105 surfactant (BASF), Iconol TDA-6 surfactant(BASF), Kraftsperse 25M surfactant (Westvaco), Nipol 2782 surfactant(Stepan), Soprophor FL surfactant (Rhone-Poulenc), Empicol LX 28surfactant (Albright & Wilson), Pluronic F108 (BASF).

In one embodiment, exemplary suitable stabilizing components includepolymers or oligomers having a molecular weight from about 250 to about10⁶, preferably from about 400 to about 10⁵, more preferably from about400 to about 10⁴, and can include, for example, homopolymers orco-polymers described in “Polymer Handbook,” 3rd Edition, edited by J.Brandrup and E. H. Immergut.

In another embodiment, exemplary suitable stabilizing components includepolyolefins such as polyallene, polybutadiene, polyisoprene,poly(substituted butadienes) such as poly(2-t-butyl-1,3-butadiene),poly(-chlorobutadiene), poly(-chloromethyl butadiene),polyphenylacetylene, polyethylene, chlorinated polyethylene,polypropylene, polybutene, polyisobutene, polybutylene oxides,copolymers of polybutylene oxides with propylene oxide or ethyleneoxide, polycyclopentylethylene, polycyclolhexyiethylene, polyacrylatesincluding polyalkylacrylates and polyarylacrylates, polymethacrylatesincluding polyalkylmethacrylates and polyarylmethacrylates,polydisubstituted esters such as poly(di-n-butylitaconate),poly(amylfumarate), polyvinylethers such as poly(butoxyethylene) andpoly(benzyloxyethylene), poly(methyl isopropenyl ketone), polyvinylchloride, polyvinyl acetate, polyvinyl carboxylate esters such aspolyvinyl propionate, polyvinyl butyrate, polyvinyl caprylate, polyvinyllaurate, polyvinyl stearate, polyvinyl benzoate, polystyrene,poly-t-butyl styrene, poly (substituted styrene), poly(biphenylethylene), poly(1,3-cyclohexadiene), polycyclopentadiene,polyoxypropylene, polyoxytetramethylene, polycarbonates such aspoly(oxycarbonyloxyhexamethylene), polysiloxanes, in particular,polydimethyl cyclosiloxanes and organo-soluble substituted polydimethylsiloxanes such as alkyl, alkoxy, or ester substitutedpolydimethylsiloxanes, liquid polysulfides, natural rubber andhydrochlorinated rubber, ethyl-, butyl- and benzyl-celluloses, celluloseesters such as cellulose tributyrate, cellulose tricaprylate, andcellulose tristearate, natural resins such as colophony, copal, andshellac, and the like, and combinations or copolymers thereof.

In still another embodiment, exemplary suitable stabilizing componentsinclude co-polymers of styrene, alkyl styrenes, isoprene, butenes,butadiene, acrylonitrile, alkyl acrylates, alkyl methacrylates, vinylchloride, vinylidene chloride, vinyl esters of lower carboxylic acids,and α,β-ethylenically unsaturated carboxylic acids and esters thereof,including co-polymers containing three or more different monomer speciestherein, as well as combinations and copolymers thereof.

In yet another embodiment, exemplary suitable stabilizing componentsinclude polystyrenes, polybutenes, for example polyisobutenes,polybutadienes, polypropylene glycol, methyl oleate,polyalkyl(meth)acrylate e.g. polyisobutylacrylate orpolyoctadecylmethacrylate, polyvinylesters e.g. polyvinyl stearate,polystyrene/ethyl hexylacrylate copolymer, and polyvinylchloride,polydimethyl cyclosiloxanes, organic soluble substituted polydimethylsiloxanes such as alkyl, alkoxy or ester substitutedpolydimethylsiloxanes, and plybutylene oxides or copolymers ofpolybutylene oxides with propylene and/or ethylene oxide. In oneembodiment, the surface active agent can be adsorbed onto the surface ofthe biocide particle, e.g., in accordance with U.S. Pat. No. 5,145,684.

Another aspect of the invention is a method of preparing a micronizedorganic biocide (e.g. penflufen) product comprising the steps of: 1)providing the organic biocide to a mill, and 2) milling the materialwith a milling media having a density greater than about 2.5 and havinga diameter between about 0.01 mm and about 0.7 mm. The density of themilling media, and especially of the milling media within the size range0.1 to 0.5 mm, is advantageously greater than about 3.5, for examplegreater than about 4, preferably greater than about 5.5, for exampleequal to or greater than about 6 grams per cubic centimeter. Ceramicmilling media is preferred over metallic milling media.

In each embodiment, the milling load is preferably about 50% or higherof the volume of the mill, though loadings between 40% and 90% areefficient. In each embodiment, advantageously water and surface activeagents or dispersants are added to the product before or during milling.In each embodiment, the product can be transported as a stable slurry,as a wettable powder, or as granules that disintegrate on mixing withwater to release the product.

Wet milling can be done in a sand grinder charged with for examplepartially stabilized zirconia beads with diameter 0.5 mm; alternatelywet milling in a rotary sand grinder with partially stabilized zirconiabeads with diameter 0.5 mm and with stirring at for example 1000 rpm; orby use of a wet-ball mill, an attritor (e.g., manufactured by MitsuiMining Ltd.), a perl mill (e.g., manufactured by Ashizawa Ltd.), or thelike. Modifications of the above processes are within the skill of oneof ordinary skill in the art, and such modifications will not bedescribed here.

A milling process using 0.5 mm high density zirconium silicate and morepreferably 0.5 mm zirconia grinding media provides further efficientattrition, especially for the removal of particles greater than about 1micron in the coarse material of penflufen.. This wet milling process isinexpensive, and all of the precipitate can be used in the injectablecopper-containing particulate wood treatment. The milling agents can bezirconia, partially stabilized zirconia, zirconium silicate, andyttrium/zirconium oxide, for example, recognizing that the more densematerials give faster particle size attrition. The size and density ofthe milling material is believed to be important, even critical, toobtaining a commercially acceptable process. The milling agent materialhaving a diameter of 2 mm or greater are ineffective over hours anddays, milling material of diameter of 1 mm is ineffective over times inthe prior art, e.g., 10 minutes to an hour, while milling agent materialhaving a diameter of 0.5 mm is effective typically after 15 minutes ofmilling.

Alternately or additionally, the organic biocide can be contained inmilled injectable solid organic biocide particulates. Generally, such asmall quantity of organic biocides are required that the d₅₀ of theorganic biocides is advantageously between about 0.2 to about 0.8 timesthe d₅₀ of the copper compounds.

The particle size distribution of the particulates in one embodiment issuch that at least about 50% by weight of the particulates have anaverage diameter, or mean particle size, between about 0.02 microns andabout 1.0 microns, or preferably at least about 50% by weight of theparticulates have an average diameter between about 0.05 microns andabout 0.5 microns.

In another embodiments of this invention, the particulate-based biocidalcomposition is substantially free of alkanolamines, e.g., thecomposition comprises less than 5% alkanolamines, preferably less than1.0% alkanolamines, or is totally free of alkanolamines.

In preferred embodiments of this invention, the particulate-basedbiocidal composition is substantially free of ammonium compounds (e.g.,ammonium hydroxide), e.g., the composition comprises less than 5%ammonia, preferably less than 1% ammonia, or is totally free of ammoniumcompounds, with the proviso that ammonium compounds whose primaryfunction is as an organic biocide are excluded.

In preferred embodiments of this invention, the biocidal composition issubstantially free of organic solvents, e.g., the slurry comprises lessthan 1% organic solvents, preferably less than 0.1% organic solvents, oris totally free of organic solvents.

The loading of biocidal composition will depend on a variety of factors,including the desired copper and/or penflufen loading in the wood, theporosity of the wood, and the dryness of the wood. Calculating theamount of copper-based compositions is well within the skill of one ofordinary skill in the art. Generally, the desired copper loading intowood is between 0.0025 and about 0.5 pounds copper per cubic foot (pcf)of wood. Generally, the desired loading of penflufen into wood isbetween about 4 and about 200 g/m³, preferably between about 8 and about80 g/m³. In certain embodiments, the current invention comprises acopper compound and penflufen in a copper:penflufen ratio of betweenabout 1:1 to about 500:1. In another preferred embodiment, the presentcomposition can further be used in combination with other knownpreservative chemicals, including boron based preservatives, such asboric acid, sodium salt of borates; triazole compounds,pentachlorophenol, and sodium fluoride. Triazoles of the woodpreservative formulations of the invention include, but are not limitedto epoxiconazole, triadimenol, propiconazole, prothioconazole,metconazole, cyproconazole, tebuconazole, flusilazole, paclobutrazol,fluconazole, isavuconazole, itraconazole, voriconazole, pramiconazole,ravuconazole, and posaconazole.

In one embodiment the biocidal composition comprises between 50 and 800ppm of one or more scale precipitation inhibitors or corrosioninhibitors, particularly nitrite compounds and organophosphonates.Nitrite compounds include, not limiting to, sodium nitrite, calciumnitrite or potassium nitrite. Alternately or additionally thecomposition may contain between about 50 and about 2000 ppm of one ormore chelators. Both of these additives are meant to inhibitprecipitation of salts such as calcium carbonate and the like, where thesource of calcium may be from the water used to make up the slurry. Thepreferred inhibitors are hydroxyethylidene diphosphonic acid (HEDP),diethylenetriamine-pentamethylenephosphonic acid (DTPMP), and/or2-phosphonobutane-1,2,4-tricarboxylic acid (PBTC). If the preservativeis in a concentrate, the composition should comprise between 10 mmolesand 100 mmoles/L of HEDP, or between 30 mmoles and 170 mmoles/L of PBTCor DTPMP. Mixtures of inhibitors are preferred, as concentrates may havemore inhibitor than can readily be solubilized therein. If thepreservative is in a solid form, the preservative should comprisebetween about 0.1 to about 1 mole HEDP per kg of particulates, orbetween about 0.17 to about 2 mole PBTC and/or DTPMP per kg ofparticulates.

The biocidal composition can contain one or more additives to aidwetting, for example surfactants. Surfactants may be in solution, oralternatively may bind to the surface, in which case they aresurface-active agents and may function as stabilizers or dispersants.Preferred dispersing agents include a surface active portion thatinteracts with the copper-containing particle and a second preferablydifferent portion, which operates to inhibit irreversible agglomerationof the copper-based particles. For example, a polyacrylate dispersingagent may include at least one carboxyl group capable of associating,such as electrostatically, with a copper-containing particle and asecond, hydrophobic portion that may operate to inhibit the permanentagglomeration of the copper-containing particles. Exemplary dispersingagents may include at least one of a surfactant, a polyacrylate, apolysaccharide, a polyaspartic acid, a polysiloxane, and a zwitterioniccompound. Exemplary compounds useful as dispersing agents are discussedin the section relating to milling. The particulate-based biocidalcompositions preferably exclude emulsifiers and surfactants.

In one embodiment of the invention, the particulate copper compound maycomprise a polymer or polymeric dispersant, collectively polymer. Inthis embodiment, the ratio of the weight of copper present in theparticles to polymer present in the particles may be at least about 100to 1, for example at least about 2 to 1, 4 to 1, 5 to 1, 7 to 1, or atleast about 10 to 1. For example, if ratio of the weight of copperpresent in the particles to the weight of polymer present in theparticles is at least about 2 to 1, the particles comprise at leastabout twice as much copper by weight as polymer. Another aspect of theinvention relates to a preservative useful for wood or wood products,the preservative preferably comprising a preferably aqueous suspensionof particulate copper compounds and particulate penflufen. If apolymeric dispersing agent is present in the suspension, the ratio ofthe weight of copper present in the copper-based particles of thesuspension to the weight of dispersing agent present in the suspensionmay be at least about 1 to 1, for example at least about 5 to 1, 10 to1, 15 to 1, 20 to 1 or at least about 30 to 1.

Dispersing agents aid particulate dispersion and to prevent aggregationof particulates. Sub-micron sized particulates have a tendency to formmuch larger aggregates. Aggregates as used herein are physicalcombinations of a plurality of similarly-sized particles, often broughttogether by van der Waals forces or electrostatic forces. If aggregatesare allowed to form they often can age into a stable aggregate thatcannot be readily broken up by mechanical agitation, for example byvigorous stirring of a slurry. Such aggregates may grow to a size wherethe aggregates are not readily injectable, or may be of a size to makethe aggregates visible, therefor giving undesired color. In preferredembodiments of the invention at least 30%, preferably at least 60%, morepreferably at least 90% by weight of the substantially crystallineparticulate copper compounds in a slurry composition are mono-disbursed,e.g., are not in aggregates. Further, the particles advantageously donot tend to agglomerate when injected into the wood. To preventparticulates from agglomerating, the concentrated slurry or paste maycomprise polymers, such as polyvinyl alcohols, polyvinyl pyrrolidones,polyalkylene glycols and polyacrylates, in quantities of 0.1 to 20% byweight, based on the weight of the particulates.

The biocidal compositions mentioned can be prepared in a manner knownper se, for example by mixing the active compounds with the liquidcarrier, and including dispersants and/or binders or fixative, and otherprocessing auxiliaries. Particulates can be provided in a concentratedslurry, in a very concentrated paste, as dry particulates, as coated dryparticulates, as part of a dry pre-mix, or any combination thereof

In one embodiment, the composition of the current invention is preparedas a concentrate. If the wood treatment is to be manufactured, stored,or transported in a wetted form, it is beneficially in a concentratedform to minimize the volume and expense of handling water. Preferablythe concentrated slurry or paste (for shipping and storing, for example,comprises between 5% and 80% by weight, for example between about 15%and 40%, of particulate copper compounds and/or penflufen, with theremainder of the concentrated slurry or paste beneficially being a fluidcarrier. The concentrated slurry or paste may further comprise solidparticulates that are carriers for one or more organic biocides, andsolid particulates comprising corrosion inhibitors. The aqueous carrierbeneficially comprises one or more additives as discussed for theslurry, including anti-oxidants, disbursing agents, other biocidal saltsand compounds, chelators, corrosion inhibitors, e.g., phosphate and/orborate salts, alkali metal hydroxides and/or carbonates, antifreeze, andthe like. The concentration of these additives will depend in part onthe degree to which the composition is expected to be diluted to make acommercially useful injectable particulate-based biocidal compositionhaving the proper copper loading for the types of wood.

In one embodiment, the material comprises A) about 30% to 70% by weightof a mixture of a particulate copper compound and particulate penflufen,e.g., copper hydroxide, for example, about 35% to 65%, such as about 38%to about 61% of a copper compound, in particulate form; B) about 10% to35% by weight, such as about 15% to about 30% of at least one dispersingagent, e.g., lignosulfonates or polyacrylates; C) between about 2.5% to20% by weight, such as about 5% to 15% of at least one wetting agent,for example, a surfactant, e.g., Morwet EP available from BartonSolvents, Inc.; D) between about 5% to about 25% by weight, such asabout 10% to 20% of at least one diluent, for example soluble andinsoluble diluents, such as those used in agricultural products, e.g.,clay, such as an attapulgite clay, or particulate carrier particlescomprising organic biocide; E) between about 0.05% to 7.5% by weight,such as about 0.1% to about 5%, of at least one antifoam agent; andoptionally F) about 2.5% to about 25%, alternatively less than about7.5%, such as less than about 5% by weight, of water.

Another aspect of the invention relates a method of preserving wood or awood product comprising injecting into wood or dispersing into a woodproduct one or more of the biocidal particulate compositions of thisinvention. The material of this invention is useful for wood, and alsofor wood products, e.g., wood composites. Exemplary wood productsinclude oriented strand board, particle board, medium densityfiberboard, plywood, laminated veneer lumber, laminated strand lumber,hardboard and the like. Preferred methods of preserving wood compositesrequire the preservative of this invention either be mixed with the woodmaterial or fibers before bonding, or more preferably injected into thewood material or fibers, followed by bonding.

In one embodiment, the wood or wood product has a surface, a thickness,a width, and a length. Preferably, the wood or wood product comprises ahomogenous distribution of micronized copper compounds and micronizedpenflufen. In one embodiment, a volume number density of thecopper-based particles 5 cm from the surface, and preferably throughoutthe interior of the wood or wood product, is at least about 50%, forexample, at least about, 60%, 70%, or 75% a volume number density of thecopper-based particles 1 cm from the surface.

The wood preservative compositions of the invention can be applied towood through dipping, brushing, spraying or vacuum/pressure treatment.Wood or wood products comprising copper compounds and penflufen inaccordance with the present invention may be prepared by subjecting thepresent composition into wood through a vacuum and/or pressure process.In a preferred embodiment, vacuum and/or pressure techniques are used toimpregnate the wood in accord with this invention including the standardprocesses, such as the “Empty Cell” process, the “Modified Full Cell”process and the “Full Cell” process, and any other vacuum and /orpressure processes which are well known to those skilled in the art. Inanother embodiment, the treating liquid may be applied by a microwave orradio frequency treating process. In this process, the wood substrate isfirst heated using a radio frequency or microwave energy. Thetemperature of the heated target zone can vary from 40° C. to 300° C.,and more preferably 80° C. to 100° C. Immediately after the heating, aliquid formulation comprising pyrazole and isothiazolinone is contactedwith the substrate. The temperature of the liquid formulation is belowthat of the heated target zone at the time the composition is applied,the difference between the temperatures of the composition and theheated target zone being sufficient to reduce pressure in the substrateafter the composition is applied. Various frequencies of radio ormicrowave energy may be used. The frequency of the radio frequency ormicrowave energy can vary from 0.1 MHz to 100 MHz, preferably between 10and 50 MHz, a more preferably from 20 to 40 MHz. Skilled persons mayreadily appreciate appropriate wavelengths outside this range. Thetreating fluid may also be applied to wood by a Microwave process.. Thecompositions of the present invention can also be used for supplementalor remedial treatment of wood in service, such as utility poles andrailroad ties. When used as remedial preservative purpose, thecompositions can be in the form of a paste- or grease-type offormulations, if desired, such that the formulation has an adhesivenature and is easy to apply to a desired location. When making a pasteor grease type of formulations, 0.5% to about 30% of an inorganic claythickening agent, or a mixture of such thickening agents, is often used.The inorganic clay thickening agents include a fibrous structure typesuch as attapulgite clay and sepiolite clay, a non-crystal structuretype such as allophone, and mixed layer structure type such asmontmorillonite and kaolinte and the above layer structure types.Examples of inorganic clay minerals, but not limited to, are:attapulgite, dickite, saponite, montmorillonite, nacrite, kaolinite,anorthite, halloysite, metahalloysite, chrysotile, lizardite,serpentine, antigorite, beidellite,stevensite, hectonite, smecnite,nacrite and sepiolite, montmorillonite, sauconite, stevensite,nontronite, saponite, hectorite, vermiculite, smecnite, sepiolite,nacrite, illite, sericite, glauconite-montmorillonite,roselite-montmorillonite, Bentone 38 (hectorite) and Bentone 34(bentonite), chlorite-vermiculite, illite-montmorillonite,halloysite-montmorillonite, kaolinite-montmorillonite. The clay mineralsemployed in the compositions of the present invention also containexchangeable cations including, but not limited to, aluminum ions,protons, sodium ions, potassium ions, calcium ions, magnesium ions,lithium ions, and the like. Among the above inorganic clay minerals,attapulgite, hectorite, bentonite, montmorillonite, sauconite, smecnite,stevensite, beidellite, nontronite, saponite, hectorite, vermiculite,nacrite, and sepiolite are particularly preferable for the presentinvention. In this embodiment, the composition of the present inventioncan be applied to the wood surface through external coating treatment.

EXAMPLES

The following examples are merely indicative of the nature of thepresent invention, and should not be construed as limiting the scope ofthe invention, nor of the appended claims, in any manner.

Example 1—Synergism.

The synergism was determined using a modified method as described byKull et al. (Applied Microbiology, 1961 (9): 538-541). The modifiedmethod is described as below:

QA/Qa+QB/Qb=SI

Where:

-   Q_(a) =concentration of substance A alone which controls a    particular decay fungus-   Q_(b)=concentration of substance B alone which controls a particular    decay fungus-   Q_(A)=concentration of substance A in the concentration of the A and    B mixture at which controls a particular decay fungus-   Q_(B)=concentration of substance B in the concentration of the A and    B mixture at which controls a particular decay fungus-   SI=1 means additivity-   SI>1 means antagonism-   SI<1 means synergism

Example 2—Synergistic Activity of a Combination of Copper Fungicide andPenflufen Against Various Wood Decay Brown Rot Fungi.

Wood cubes measuring 19 mm×19 mm×19 mm were prepared from southern pinesapwood. One set of wood cubes were pressured treated with serialtreating solutions containing penflufen fungicide. A second set of woodcubes were pressure treated with treating solutions containing thecopper fungicide. A third set of wood cubes were pressure treated withtreating solutions containing a mixture of the copper and penflufen. Thetreated wood samples were exposed to various fungi to conduct alaboratory decay resistance test following protocols as described inAmerican Wood Protection Association Standard E10-2015. Before and afterexposure to fungi, the wood samples were weighed to determine the weightpercent loss. No weight loss means complete control of the fungalattack. The results are reported in Table 1.

TABLE 1 Copper Retention in Cu to Penflufen Brown Rot Fungi Wood as Cuin kg/m³ Ratio SI Gloeophyllum trabeum 0.91 228 to 1 0.37 Fibroporiaradiculosa 0.91  23 to 1 0.79 Postia placenta 0.91 114 to 1 0.95Coniophora Postia 0.91 228 to 1 0.79 puteanaExample 3—Wood Stakes Treated with Amine Copper and Penflufen FieldEfficacy Testing.

Wood stakes measuring 19 mm×19 mm×450 mm were prepared from southernpine sapwood. The wood stakes were treated with treating solutionscontaining a copper ethanolamine solution and a penflufen emulsion atdifferent ratios varying from copper:penflufen of 5:1 to 200:1. Thetreated wood stakes were installed in field testing plots such asGainesville, Fla. and Maunawili, HI, and both testing locations havebeen well established to have severe decay hazard. The field stakes wereinspected for efficacy against decay fungi and termite annually, and thetest were conducted following protocols as described in American WoodProtection Association Standard E7. The annual inspection results fromboth filed locations indicated that wood stakes treated with copper andpenflufen are resistant to decay and termite attack.

Example 4—Wood Stakes Treated with Micronized Copper and Penflufen FieldEfficacy Testing.

Wood stakes measuring 19 mm x 19 mm x 450 mm were prepared from southernpine sapwood. The wood stakes were treated with treating solutionscontaining micronized copper fungicide and a penflufen at differentratios varying from copper:penflufen of 5:1 to 200:1. The treated woodstakes were installed in field testing plots such as Gainesville, Fla.and Maunawili, HI, and both testing locations have been well establishedto have severe decay hazard. The field stakes were inspected forefficacy against decay fungi and termite annually, and the test wereconducted following protocols as described in American Wood ProtectionAssociation Standard E7. The annual inspection results from both filedlocations indicated that wood stakes treated with copper and penflufenare resistant to decay and termite attack.

Example 5—Wood Stakes Treated with Micronized Penflufen Field EfficacyTesting.

Southern pine wood samples were treated with treating solutionscontaining a micronized penflufen at different loadings in wood varyingfrom 10 to 250 grams per cubic meter. The treated wood stakes wereinstalled in field testing plots such as Gainesville, Fla. andMaunawili, HI, and both testing locations have been well established tohave severe decay hazard. The field stakes were inspected for efficacyagainst decay fungi and termite annually, and the test were conductedfollowing protocols as described in American Wood Protection AssociationStandard E16. The annual inspection results from both filed locationsindicated that wood stakes treated with micronized penflufen areresistant to decay and termite attack.

Example 6—Preparation of Micronized Penflufen

Penflufen was mixed with a dispersant in water medium. The mixtureslurry was mixed for about 10 minutes, and then transferred to a ballmill containing zirconia grinding media according to the presentinvention. The slurry was ground for about 2 hours and stable micronizedpenflufen dispersion was obtained. The particle size of the penflufendispersion was monitored by measuring its particle size. The results arereported in Table 2.

TABLE 2 Particle Size Stability of Penflufen Dispersion at DifferentTemperatures 4° C. 24° C. 32° C. Test d₅₀, D₉₅, Mean, d₅₀, D₉₅, Mean,d₅₀, D₉₅, Mean, Duration μm μm μm μm μm μm μm μm μm Initial 0.298 0.4900.311 0.298 0.490 0.311 0.298 0.490 0.311 1 Month 0.310 0.495 0.3190.315 0.497 0.323 0.331 0.505 0.341 4 Months 0.312 0.496 0.321 0.3170.498 0.325 0.323 0.500 0.331 6 months 0.309 0.494 0.316 0.307 0.4940.315 0.336 0.506 0.343

Example 7—Preparation of The Mixture of Micronized Copper and MicronizedPenflufen

Micronized copper was prepared by milling a slurry of basic coppercarbonate and micronized penflufen was prepared by milling penflufensolid. The final micronized copper and micronized penflufen were mixedtogether at various ratios, and the particle size of the final mixturewas monitored. The results are reported in Tables 3 -5. The level ofcopper and penflufen in the mixture was also monitored by chemicallyanalyzing the copper content and penflufen content, and the result isgiven in Table 6.

TABLE 3 Particle Size Stability of Mixture of Penflufen in Dispersed BCC(Cu:Penflufen = 25:1) at Different Temperatures 4° C. 24° C. 38° C. Testd₅₀, D₉₅, Mean, d₅₀, D₉₅, Mean, d₅₀, D₉₅, Mean, Duration μm μm μm μm μmμm μm μm μm Initial 0.365 0.532 0.369 0.365 0.532 0.369 0.365 0.5320.369 3 weeks 0.365 0.500 0.358 0.362 0.506 0.365 0.369 0.521 0.373 6weeks 0.339 0.498 0.344 0.361 0.522 0.365 — — — 6 months 0.353 0.5050.357 0.357 0.513 0.361 0.356 0.510 0.360

TABLE 4 Particle Size Stability of Penflufen in Dispersed BCC(Cu:Penflufen = 50:1) at Different Temperatures. 4° C. 24° C. 38° C.Test d₅₀, D₉₅, Mean, d₅₀, D₉₅, Mean, d₅₀, D₉₅, Mean, Duration μm μm μmμm μm μm μm μm μm Initial 0.365 0.531 0.370 0.365 0.531 0.370 0.3650.531 0.370 3 weeks 0.349 0.493 0.351 0.366 0.508 0.368 0.369 0.5270.373 6 weeks 0.334 0.491 0.338 0.366 0.529 0.370 — — — 6 months 0.3370.493 0.341 0.360 0.521 0.364 0.361 0.523 0.366

TABLE 5 Particle Size Stability of Mixture of Penflufen in Dispersed BCC(Cu:Penflufen = 100:1) at Different Temperatures. 4° C. 24° C. 38° C.Test d₅₀, D₉₅, Mean, d₅₀, D₉₅, Mean, d₅₀, D₉₅, Mean, Duration μm μm μmμm μm μm μm μm μm Initial 0.365 0.530 0.370 0.365 0.530 0.370 0.3650.530 0.370 3 weeks 0.355 0.499 0.357 0.362 0.508 0.365 0.372 0.5250.375 6 weeks 0.352 0.505 0.356 0.363 0.527 0.368 — — — 6 months 0.3550.507 0.359 0.358 0.516 0.363 0.358 0.515 0.362

TABLE 6 Stability of Active % Penflufen in Dispersed BCC Solution atDifferent Temperatures. Cu:Penflufen = Cu:Penflufen = Cu:Penflufen =Test 25:1 50:1 100:1 Duration 24° C. 38° C. 24° C. 38° C. 24° C. 38° C.Initial 1.22 1.22 0.66 0.66 0.33 0.33  1 week 1.24 1.21 0.66 0.66 0.330.33  2 weeks 1.21 1.22 0.66 0.67 0.33 0.33  3 weeks 1.23 1.22 0.67 0.660.33 0.32  4 weeks 1.23 1.23 0.67 0.67 0.33 0.33  8 weeks 1.24 1.21 0.680.66 0.34 0.33 12 weeks 1.22 1.42 0.65 0.64 0.33 0.31 16 weeks 1.21 1.090.67 0.65 0.33 0.31 24 weeks 1.34 1.20 0.69 0.66 0.34 0.32 48 weeks 1.221.24 0.68 0.67 0.34 0.33

Example 8—Bio-Efficacy of Dispersed Penflufen Against Wood Decay Fungi.

Wood cubes measuring 19 mm×19 mm×19 mm were prepared from southern pinesapwood. The wood cubes were pressure treated with treating solutionscontaining micronized penflufen. The treated wood samples were exposedto various fungi to conduct a laboratory decay resistance test followingprotocols as described in American Wood Protection Association StandardE10-2015. Before and after exposure to fungi, the wood samples wereweighed to determine the weight percent loss. The test results aresummarized in Table 7.

TABLE 7 Mean Percent Weigh Loss of Treated Wood Cubes at DifferentPenflufen Retention. Decay Fungi Penflufen Coniophora GloeophyllumFibroporia Postia Retention, g/m³ puteana trabeum radiculosa placenta 81.4 3.1 12.0 3.5 12 1.6 2.9 10.4 1.9 16 1.6 3.6 8.2 2.1 24 1.5 3.0 8.21.2 32 1.1 3.5 5.4 1.2 48 1.4 3.0 5.7 1.1 64 2.0 1.6 4.4 1.1 80 1.3 2.03.0 1.3 0 (Untreated 25.3 41.7 49.1 47.5 SP)Example 9—Preparation of Wood Preservative Treating Solution ComprisingMicronized Copper and Penflufen actives

A series of wood preservative treating solutions were prepared by mixinga micronized copper concentrate and a penflufen concentrate with water.Alternatively, the wood preservative treating solutions can be preparedby diluting micronized copper+penflufen concentrate with water. Otheradditives, such as mold inhibitors, water repellent, and/or pigments canbe added to the treating solutions as well. The penflufen can beprepared either as an emulsion concentrate (EC) or asuspension/dispersion concentrate (SC) or combination of suspoemulsionconcentrate (SEC), or a soluble solution concentrate. After preparationof the treating solutions, the concentration of both copper andpenflufen actives were monitored and measured over a 16-week periodunder ambient conditions. The results as shown in Table 8 indicate thatthere are minimal to negligible changes in the active concentration ofcopper and penflufen. The results further indicate that the combinationof copper/penflufen composition disclosed in the current application isa viable formulation for treating wood.

TABLE 8 The Active Concentration of Copper and Penflufen during Storageunder Ambient Conditions. 0 Weeks 2 Weeks 4 Weeks 8 Weeks 16 Weeks CuPenflufen Cu Penflufen Cu Penflufen Cu Penflufen Cu Penflufen (%) (%)(%) (%) (%) (%) (%) (%) (%) (%) Solution #1 0.198 0.0069 0.200 0.00660.200 0.0065 0.200 0.0071 0.198 0.0066 Solution #2 0.497 0.0177 0.4990.0174 0.500 0.0174 0.505 0.0180 0.501 0.0173 Solution #3 0.193 0.00370.194 0.0035 0.194 0.0035 0.195 0.0034 0.195 0.0035 Solution #4 0.4950.0097 0.500 0.0094 0.499 0.0093 0.497 0.0093 0.497 0.0094 Solution #50.195 0.0017 0.196 0.0016 0.196 0.0015 0.197 0.0014 0.196 0.0015Solution #6 0.491 0.0046 0.496 0.0043 0.502 0.0043 0.499 0.0045 0.5020.0045

What is claimed is: 1-96. (canceled)
 97. A method of preparing a woodpreservative composition comprising the steps of milling a slurry ofpenflufen and a dispersant in a carrier with a high density grindingmedia and diluting the slurry with the same or a different carrier toprepare a wood preservative composition or a concentrated woodpreservative composition.
 98. The method of claim 97, wherein the highdensity grinding media has a diameter between 0.01 and 5.0 mm.
 99. Themethod of claim 97, wherein the high density grinding media has adiameter between 0.1 and 0.5 mm.
 100. The method of claim 97, whereinthe high density grinding media has a density of 2.5 g/cc or higher.101. The method of claim 97, wherein the high density grinding media hasa density of 3.5 g/cc or higher.
 102. The method of claim 97, whereinthe weight ratio of penflufen to dispersant is between about 1:500 toabout 1000:1.
 103. The method of claim 97, wherein the weight ratio ofpenflufen to dispersant between about 1:1 to about 100:1.
 104. Themethod of claim 97, wherein the particles in the wood preservativecomposition have a particle size between about 5 to 5000 nanometers.